1. Field of the Invention
The present invention relates to a fusible link unit with fuse circuit structures each containing terminal portions connected with fusible members, wherein the terminal portions are linked like a chain.
2. Related Art
The fusible link units of this type are generally known. (See Japanese Patent Publication No. JP-A-2000-133114, for example). FIGS. 9 through 13B shows one of such the fusible link units. The fusible link unit designated by reference numeral 100, as shown in FIGS. 9 and 10, is generally composed of first and second fuse circuit structures 101 and 102 and a housing 103 into which those fuse circuit structures 101 and 102 a reassembled. The first fuse circuit structure 101, as illustrated in detail in FIG. 11, is made up of a linking plate 104, a plurality of female terminal portions 106a and screw fixing terminal portions 106b, which are coupled through fusible members 105 to the linking plate 104, a battery terminal portion 107 extended from one end of the linking plate 104, and a common terminal portion 108 coupled through a fusible member 105a to the other end of the linking plate 104. The first fuse circuit structure 101 is formed by pressing a conductive plane plate.
The second fuse circuit structure 102, as illustrated in detail in FIG. 12, is made up of a linking plate 109, a plurality of female terminal portions 111a and screw fixing terminal portions 111b, which are coupled through fusible members 110 to the linking plate 109, a battery terminal portion 107 extended from one end of the linking plate 104, and a common terminal portion 112 extended from the other end of the linking plate 109. The first fuse circuit structure 101 is formed by pressing a conductive plane plate.
As shown in FIGS. 9 and 10, the housing 103 is shaped like a rectangular parallelepiped, and contains a circuit-structure accommodating chamber 114 with an opening 113 open to the upper. The housing further includes a plurality of connector housing portions 115 and a plurality of terminal supports 116, which are provided under the circuit-structure accommodating chamber 114.
As shown in FIG. 9, the first and second fuse circuit structures 101 and 102 are each inserted into the circuit-structure accommodating chamber 114, through the opening 113 of the housing 103. In this case, an extending direction of the flat surface of each fuse circuit structure is an insertion direction, and the terminal portions (106a, 106b, 111a, 111b) of the fuse circuit structure are first inserted as an insertion tip part. When the first and second fuse circuit structures 101 and 102 are completely inserted into the circuit-structure accommodating chamber, the linking plates 104 and 109 of those fuse circuit structures 101 and 102 are located within the circuit-structure accommodating chamber 114. The terminal portions 106a, 106b, 111a, and 111b are set at predetermined positions of the connector housing portions 115 and the terminal supports 116.
Next, the common terminal portions 108 and 112 of the first and second fuse circuit structures 101 and 102 are fastened together to the housing 103 by a bolt 117. The first and second fuse circuit structures 101 and 102 are electrically connected to each other to thereby form a desired fuse circuit. Connected to the female terminal portions 106a and 111a within the connector housing portions 115 are the terminals of the mating connectors (not shown). Connected to the battery terminal 107 and the screw fixing terminal portions 106b and 111b are screw fixing terminals 119 of the mating connectors by nut members 118 as press fit and screws (not shown). The terminals of the connectors (not shown) and the screw fixing terminals 119 are connected to loads by way of cables 120. Power source is distributed from a battery to those loads, through a fuse circuit. When shortcircuiting occurs in any of the loads and overcurrent flows into the related fusible member 105 (110), the fuse member burns out by heating to thereby prevent trouble by overcurrent.
In the fusible link unit 100 thus constructed, the first and second fuse circuit structures 101 and 102, shaped like flat plates, are assembled into the housing 103 to thereby form a unit. Therefore, a fuse circuit containing a number of fusible members (fuses) 105 and 110 may be made compact.
In the fusible link unit 100 mounted on a vehicle, all the terminal portions 106a, 106b, 11a, and 111b are not used in every application. In some type or grade of the vehicle to which the fusible link unit is applied, some of those terminal portions 106a, 106b, 11a, and 111b are not used. Specifically, there is a case where some of the screw fixing terminal portions 106b and 111b are not in use. In this case, the following problem arises.
As best illustrated in FIGS. 13A and 13B, each of the screw fixing terminal portions 106b and 111b is set in a state that the back surface and the sides of each screw fixing terminal portion are merely put along the terminal support 116, and the front surface of the screw fixing terminal portion is exposed to outside. Accordingly, during the assembling stage or transportation, the edge of any of the screw fixing terminal portions 106b and 111b is caught on something, the screw fixing terminal portion as caught is raised from the terminal support 116by its plastic deformation. In its raised state, it easily vibrates when it receives a vibration from outside, and generates rattling sounds.
One possible approach to prevent the noise sounds that result from the raising of the screw fixing terminal portion 106b (11b) and the vibration coming from outside is to fasten the screw fixing terminal portions 106b and 111b, even if not in use, by screws. However, this approach results in increase of the cost to manufacture and decrease of the efficiency of the assembling work.